Primary treatment for glucose intolerance is strict adherence to a diet which minimizes postprandial glucose response, and in many cases, use of medications (insulin or oral hypoglycemic agents). The American Diabetes Association (ADA) currently recommends a diet in which protein accounts for 12-20% total calories (kcal), carbohydrate for 50-60% kcal, and fat for the remaining kcal (about 30%). Diabetes Care 2:250-253, 1979. The ADA also recommends consumption of complex carbohydrates that are high in dietary fiber (40 g/day for men, 25 g/day for women), and consumption of fats that are low in cholesterol (&lt;300 mg/day) and low in saturated fatty acids (polyunsaturated fatty acids : saturated fatty acids or P:S ratio=1 or greater), Diabetes Outlook 21:1-8, 1986.
Most currently available liquid enteral formulas comply, for the most part, with the ADA recommendations. One such enteral formula sold by Fresenius Diatetik, Bad Homburg, West Germany under the name Diabetiker-Flussignahrung, contains 43% kcal as carbohydrate, 37% as fat and 20% kcal as protein. Enteral formulas commonly used in patients with glucose intolerance in the United States include Compleat.RTM. nutritional formula (Sandoz Nutrition, Minneapolis, Minn.), which contains 16% kcal as protein, 48% kcal as carbohydrate, 36% kcal from fat, and dietary fiber from fruits and vegetables, Enrich.RTM. nutritional formula (Ross Laboratories, Columbus, Ohio), which contains 14.5% kcal as protein, 55% kcal as carbohydrate, 30.5% kcal as fat, and dietary fiber from soy polysaccharide and Osmolite.RTM. nutritional formula (Ross Laboratories, Columbus, Ohio) which contains 14.0% kcal as protein, 54.6% kcal as carbohydrate and 31.4% kcal as fat.
The primary problem in following the ADA guidelines with liquid diets is that these formulas empty rapidly from the stomach and are absorbed very efficiently in the upper segments of the small bowel. Stevens et al, JPEN 3:32, 1979, have shown that 66% each of a 500 kcal feeding of Osmolite nutritional formula and two other enteral formula diets emptied from the stomach in one hour, and that 95% of each feeding empties in two hours. This is at least twice as fast as the emptying rate of an isocaloric solid food meal.
Because of the rapid emptying rate of liquid nutritional formulas, rapid absorption of their carbohydrate sources also occurs, which increases potential for hyperglycemia in patients with glucose intolerance. Cashmere et al, Fed Proc 43:392, 1984, have shown that blood glucose response from a 500 kcal feeding, each, of Compleat and Enrich nutritional formulas peaks in only 30 minutes in healthy volunteers. This is as rapid as the absorption rate of free glucose. Additionally, a study conducted at the University of Chicago, by Dreutzler et al, (unpublished), has shown that 5 day consumption of Enrich nutritional formula as the sole source of nutrition resulted in an elevated glucose response curve in patients with Type II diabetes mellitus; following 5 day consumption of the diet, peak glucose response was 5% higher than baseline, and integrated area under the glucose response curve was almost 8% higher than baseline. Data from these studies indicate that the current ADA dietary guidelines are inappropriate for liquid nutritional diets.
Several studies have shown that manipulation of certain dietary components may be beneficial to glucose intolerant individuals. For example, fructose is known to be more slowly absorbed than glucose and has been reported to lower postprandial blood glucose and insulin response. Koivistoinen et al, Carbohydrate Sweeteners in Foods and Nutrition, Academic Press, London, 1980. Dietary fiber has been reported to lower posprandial glucose response in patients with diabetes. Kay et al, Diabetologia 20:18-21, 1981.
One study has suggested adding myoinositol to the diet of diabetic patients in order to prevent decreases in tissue myoinositol which are common in patients having diabetes mellitus and result in deranged sodium potassium ATPase regulation which produces a functional derangement within nerves, retina and glomerulus. Diabetic Outlook 21:2, 1986. The amino acid carnitine has been reported to reduce serum lipids, triglycerides, cholesterol and fatty acids in patients with diabetes mellitus. Abdel-Aziz et al, Nutr. Reports International 29:1071-1079, 1984. Chromium is known to function as a component of an organic complex with nicotinic acid and amino acids to form glucose tolerance factor required to maintain glucose homeostasis. Wallach, J. Amer. Coll. Nutr. 4:107-120, 1985.